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1.
J Asian Nat Prod Res ; 22(3): 201-216, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31497993

RESUMO

As the continuous scientific research, seven new 1-oxygenated cholestane glycosides named osaundersiosides 1 A - 1 G were isolated from an EtOH extract of the bulbs of Ornithogalum saundersiae. Their structures were deduced by means of spectroscopic data, chemical evidence and the results of hydrolytic cleavage. The cytotoxicity and anti-inflammatory effects of osaundersiosides 1 A - 1 G were evaluated, but none of them displayed significant activities. [Formula: see text].


Assuntos
Antineoplásicos Fitogênicos , Colestanos , Ornithogalum , Glicosídeos , Estrutura Molecular
2.
Geobiology ; 18(3): 326-347, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-31865640

RESUMO

Lipid biomarker assemblages preserved within the bitumen and kerogen phases of sedimentary rocks from the ca. 780-729 Ma Chuar and Visingsö Groups facilitate paleoenvironmental reconstructions and reveal fundamental aspects of emerging mid-Neoproterozoic marine communities. The Chuar and Visingsö Groups were deposited offshore of two distinct paleocontinents (Laurentia and Baltica, respectively) during the Tonian Period, and the rock samples used had not undergone excessive metamorphism. The major polycyclic alkane biomarkers detected in the rock bitumens and kerogen hydropyrolysates consist of tricyclic terpanes, hopanes, methylhopanes, and steranes. Major features of the biomarker assemblages include detectable and significant contribution from eukaryotes, encompassing the first robust occurrences of kerogen-bound regular steranes from Tonian rocks, including 21-norcholestane, 27-norcholestane, cholestane, ergostane, and cryostane, along with a novel unidentified C30 sterane series from our least thermally mature Chuar Group samples. Appreciable values for the sterane/hopane (S/H) ratio are found for both the free and kerogen-bound biomarker pools for both the Chuar Group rocks (S/H between 0.09 and 1.26) and the Visingsö Group samples (S/H between 0.03 and 0.37). The more organic-rich rock samples generally yield higher S/H ratios than for organic-lean substrates, which suggests a marine nutrient control on eukaryotic abundance relative to bacteria. A C27 sterane (cholestane) predominance among total C26 -C30 steranes is a common feature found for all samples investigated, with lower amounts of C28 steranes (ergostane and crysotane) also present. No traces of known ancient C30 sterane compounds; including 24-isopropylcholestanes, 24-n-propylcholestanes, or 26-methylstigmastanes, are detectable in any of these pre-Sturtian rocks. These biomarker characteristics support the view that the Tonian Period was a key interval in the history of life on our planet since it marked the transition from a bacterially dominated marine biosphere to an ocean system which became progressively enriched with eukaryotes. The eukaryotic source organisms likely encompassed photosynthetic primary producers, marking a rise in red algae, and consumers in a revamped trophic structure predating the Sturtian glaciation.


Assuntos
Eucariotos , Biomarcadores , Colestanos , Sedimentos Geológicos , Fotossíntese
3.
Phytochemistry ; 164: 206-214, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31177053

RESUMO

Eight undescribed cholestane glycosides named osaundersioside A-H, along with three previously known compounds named osaundersioside I-K were isolated from Ornithogalum saundersiae Baker bulbs (Asparagaceae). Their structures were elucidated by extensive spectroscopic analysis and chemical methods. All isolates were evaluated for their cytotoxic activity and inhibitory effects on lipopolysaccharide (LPS)-induced nitric oxide (NO) production. Osaundersioside C was thus determined to exhibit specific cytotoxicity towards MCF-7 cell line with an IC50 value of 0.20 µM, Osaundersioside H exhibited inhibitory effect on NO production in macrophages at the concentration of 10-5 M, with inhibition rate of 56.81%.


Assuntos
Anti-Inflamatórios não Esteroides/farmacologia , Antineoplásicos Fitogênicos/farmacologia , Asparagaceae/química , Colestanos/farmacologia , Glicosídeos/farmacologia , Animais , Anti-Inflamatórios não Esteroides/química , Anti-Inflamatórios não Esteroides/isolamento & purificação , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/isolamento & purificação , Proliferação de Células/efeitos dos fármacos , Colestanos/química , Colestanos/isolamento & purificação , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Glicosídeos/química , Glicosídeos/isolamento & purificação , Humanos , Lipopolissacarídeos/antagonistas & inibidores , Lipopolissacarídeos/farmacologia , Células MCF-7 , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Camundongos , Estrutura Molecular , Óxido Nítrico/antagonistas & inibidores , Óxido Nítrico/biossíntese , Casca de Planta/química , Raízes de Plantas/química , Relação Estrutura-Atividade
4.
Eur J Med Chem ; 168: 78-86, 2019 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-30798054

RESUMO

22-Oxocholestanes bearing the oxime functionality in the side chain have been synthesized from diosgenin and evaluated in vivo as anti-inflammatory agents in an acute inflammation mouse ear model, against the commercial glucocorticoid dexamethasone. The final compounds were all regioselectively obtained with an E configuration at the oxime double bond. The title compounds reduced ear-induced inflammation and edema. The most active oximes repressed the expression of proinflammatory genes TNF-α, COX-2, and IL-6; including macrophage migration inhibitory factor. Overall, our data suggest that 22-oxocholestane oximes exert a strong in vivo anti-inflammatory activity.


Assuntos
Anti-Inflamatórios não Esteroides/farmacologia , Colestanos/farmacologia , Otopatias/tratamento farmacológico , Edema/tratamento farmacológico , Inflamação/tratamento farmacológico , Oximas/farmacologia , Animais , Anti-Inflamatórios não Esteroides/síntese química , Anti-Inflamatórios não Esteroides/química , Colestanos/síntese química , Colestanos/química , Ciclo-Oxigenase 2/genética , Ciclo-Oxigenase 2/metabolismo , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Otopatias/metabolismo , Edema/metabolismo , Inflamação/metabolismo , Interleucina-6/genética , Interleucina-6/metabolismo , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Masculino , Camundongos , Estrutura Molecular , Oximas/síntese química , Oximas/química , Relação Estrutura-Atividade , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/metabolismo
5.
Nat Commun ; 10(1): 225, 2019 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-30644384

RESUMO

Transient oligomeric species formed during the aggregation process of the 42-residue form of the amyloid-ß peptide (Aß42) are key pathogenic agents in Alzheimer's disease (AD). To investigate the relationship between Aß42 aggregation and its cytotoxicity and the influence of a potential drug on both phenomena, we have studied the effects of trodusquemine. This aminosterol enhances the rate of aggregation by promoting monomer-dependent secondary nucleation, but significantly reduces the toxicity of the resulting oligomers to neuroblastoma cells by inhibiting their binding to the cellular membranes. When administered to a C. elegans model of AD, we again observe an increase in aggregate formation alongside the suppression of Aß42-induced toxicity. In addition to oligomer displacement, the reduced toxicity could also point towards an increased rate of conversion of oligomers to less toxic fibrils. The ability of a small molecule to reduce the toxicity of oligomeric species represents a potential therapeutic strategy against AD.


Assuntos
Doença de Alzheimer/tratamento farmacológico , Peptídeos beta-Amiloides/metabolismo , Colestanos/uso terapêutico , Fragmentos de Peptídeos/metabolismo , Espermina/análogos & derivados , Peptídeos beta-Amiloides/efeitos dos fármacos , Animais , Caenorhabditis elegans , Linhagem Celular Tumoral , Colestanos/farmacologia , Avaliação Pré-Clínica de Medicamentos , Fragmentos de Peptídeos/efeitos dos fármacos , Espermina/farmacologia , Espermina/uso terapêutico
6.
Appl Biochem Biotechnol ; 188(3): 635-662, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30613863

RESUMO

Modification of steroid molecules by introducing heterocyclic ring into the core structure of steroids has been utilized as an attractive approach for either cancer prognosis or diagnosis. Several new cholestanoheterocyclic steroids were synthesized, and analytical and spectral data proved the validity of the novel synthesized steroid derivatives. The cytotoxicity of synthesized compounds 3, 4, 5, 7, 9, 10, 13, 15b, and 16b was evaluated using human colorectal cancer HCT 116 and Caco-2, cervical cancer HeLa, hepatoma HepG2, and breast cancer MCF7 cell lines. Intriguingly, compound 13 has the highest cytotoxic effect when applied on the majority of cancer cells. In conclusion, compound 13 may be considered as a promising anticancer candidate against all cancer cell lines, because it recorded the lowest IC50 of the majority of the cancer cell lines used. Furthermore, a molecular docking study was employed to determine the binding modes against aromatase cytochrome P450 (CYP19), cyclin-dependent kinase 2 (CDK2), and B-cell lymphoma (BCL-2) proteins, which are major proteins involved in the pathogenesis of cancer. Molecular docking analyses revealed that compounds 13, 3, and 5 (free energy of binding = - 9.2, - 9.1, and - 9.0 kcal/mol, respectively) were the best docked ligand against aromatase CYP19; compounds 16b, 3, 9, and 10 (free energy of binding = - 9.6, - 9.3, and - 9.2 kcal/mol, respectively) were the best docked ligand against CDK2, while compounds 15b, 16b, and 13 (free energy of binding = - 9.1, - 9.0, and- 8.7 kcal/mol, respectively) were the best docked ligand against BCL2. In conclusion, compounds 3, 13, and 16b were the most promising compounds with the lowest IC50s against most of the tested cancer cell lines, and they displayed the lowest binding energies, critical hydrogen bonds, and hydrophobic interactions with the three molecular targets compared to other tested compounds.


Assuntos
Antineoplásicos/farmacologia , Colestanos/química , Compostos Heterocíclicos/síntese química , Compostos Heterocíclicos/farmacologia , Esteroides/síntese química , Esteroides/farmacologia , Linhagem Celular Tumoral , Compostos Heterocíclicos/química , Humanos , Análise Espectral/métodos , Esteroides/química
7.
J Nat Med ; 73(1): 131-145, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30327993

RESUMO

A search for cytotoxic cholestane glycosides from Ornithogalum saundersiae bulbs resulted in the isolation of three new OSW-1 analogues (1-3), a new cholestane bisdesmoside (4), a 5ß-cholestane diglycoside (5), and four new 24(23 → 22)-abeo-cholestane glycosides (6-9), together with 11 known cholestane glycosides (10-20), including OSW-1 (11). The structures of 1-9 were determined based on conventional spectroscopic analysis and chemical evidence. As expected, based on previous data, 1-3 exhibited potent cytotoxic activity against HL-60 human promyelocytic leukemia cells and A549 human lung adenocarcinoma cells. Furthermore, the ability of OSW-1 to induce apoptosis in HL-60 cells was examined. Aggregation of nuclear chromatin, accumulation of the sub-G1 cells, DNA fragmentation, and caspase-3 activation were assessed in HL-60 cells treated with OSW-1, providing evidence for OSW-1-induced apoptosis in HL-60 cells. No mitochondrial membrane potential or release of cytochrome c into the cytoplasm were observed in the OSW-1-treated apoptotic HL-60 cells, indicating that a mitochondria-independent signaling pathway is involved in apoptotic cell death.


Assuntos
Colestanos/química , Colestenonas/metabolismo , Glicosídeos/química , Células HL-60/metabolismo , Mitocôndrias/metabolismo , Ornithogalum/química , Saponinas/metabolismo , Apoptose , Humanos , Transdução de Sinais
8.
Spectrochim Acta A Mol Biomol Spectrosc ; 210: 372-380, 2019 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-30502725

RESUMO

Ganoderic Acids (GAs) are the major medicinal compounds in Ganoderma lucidum used as traditional Chinese medicine since ancient times. Ganoderic acid A (GAA) is the first discovered ganoderic acids reported in the literature, which is also one of most abundant triterpenoids of Ganoderma lucidum. Especially, GAA has been extensively investigated in recent decades for its positive medicinal activities. However, the vibrational properties of GAs have rarely been studied or reported. In this work, we focused on the typical GAA and studied the infrared (IR) and Raman spectra based on both experiments and DFT calculations. As such, we could not only achieve the assignments of the vibrational modes, but also from the IR and Raman spectra, we found that the spectral region from 1500 cm-1 to 1800 cm-1 is particularly useful for distinguishing different types of GAs. In addition, its dehydrogenated derivative ganoderenic acid A (GOA) was also studied, which could be identified due to its spectral feature of strong IR and Raman bands around 1620 cm-1. This work therefore may facilitate the application of IR and Raman spectroscopies in the inspection and quality control of Ganoderma lucidum.


Assuntos
Ácidos Heptanoicos/química , Lanosterol/análogos & derivados , Espectrofotometria Infravermelho/métodos , Análise Espectral Raman/métodos , Colestanos/química , Teoria da Densidade Funcional , Lanosterol/química , Estrutura Molecular , Reishi/química , Espectroscopia de Infravermelho com Transformada de Fourier , Vibração
9.
Fitoterapia ; 130: 241-246, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30196076

RESUMO

Three new cholestane-type sterols bearing an unusual ∆22-24-oxo side chain, namely, dictyoptesterols A-C (1-3), were isolated from the brown alga Dictyopteris undulata Holmes, together with five known strutural analogues (4-8). Their structures were elucidated on the basis of by extensive spectroscopic analysis. The absolute configurations of the steroidal nuclei of the new compounds were proposed by a comparison of NMR data with those of related known compounds as well as biogenetic considerations. All of the isolates were evaluated in vitro for their potential to inhibit protein tyrosine phosphatase-1B (PTP1B) activity. The results showed that compounds 1-5 exhibited different levels of PTP1B inhibitory activities with IC50 values ranging from 3.03 ±â€¯0.76 to 15.01 ±â€¯2.88 µM. In particular, compounds 3 and 4 showed promising inhibitory effects towards PTP1B with IC50 values of 3.03 ±â€¯0.76 and 3.72 ±â€¯0.40 µM, respectively, when compared to the positive control oleanolic acid (IC50, 2.83 ±â€¯0.39 µM). The chemotaxonomic significance of these isolated ∆22-24-oxo cholestanes has also been discussed.


Assuntos
Colestanos/isolamento & purificação , Inibidores Enzimáticos/isolamento & purificação , Feófitas/química , Fitosteróis/isolamento & purificação , Proteína Tirosina Fosfatase não Receptora Tipo 1/antagonistas & inibidores , China , Colestanos/farmacologia , Inibidores Enzimáticos/farmacologia , Estrutura Molecular , Fitosteróis/farmacologia
10.
ACS Chem Biol ; 13(8): 2308-2319, 2018 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-29953201

RESUMO

The aggregation of α-synuclein, an intrinsically disordered protein that is highly abundant in neurons, is closely associated with the onset and progression of Parkinson's disease. We have shown previously that the aminosterol squalamine can inhibit the lipid induced initiation process in the aggregation of α-synuclein, and we report here that the related compound trodusquemine is capable of inhibiting not only this process but also the fibril-dependent secondary pathways in the aggregation reaction. We further demonstrate that trodusquemine can effectively suppress the toxicity of α-synuclein oligomers in neuronal cells, and that its administration, even after the initial growth phase, leads to a dramatic reduction in the number of α-synuclein inclusions in a Caenorhabditis elegans model of Parkinson's disease, eliminates the related muscle paralysis, and increases lifespan. On the basis of these findings, we show that trodusquemine is able to inhibit multiple events in the aggregation process of α-synuclein and hence to provide important information about the link between such events and neurodegeneration, as it is initiated and progresses. Particularly in the light of the previously reported ability of trodusquemine to cross the blood-brain barrier and to promote tissue regeneration, the present results suggest that this compound has the potential to be an important therapeutic candidate for Parkinson's disease and related disorders.


Assuntos
Colestanos/farmacologia , Doença de Parkinson/tratamento farmacológico , Agregados Proteicos/efeitos dos fármacos , Agregação Patológica de Proteínas/prevenção & controle , Espermina/análogos & derivados , alfa-Sinucleína/metabolismo , Animais , Caenorhabditis elegans/fisiologia , Linhagem Celular , Colestanos/uso terapêutico , Modelos Animais de Doenças , Humanos , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Doença de Parkinson/metabolismo , Agregação Patológica de Proteínas/metabolismo , Espermina/farmacologia , Espermina/uso terapêutico
11.
Vascul Pharmacol ; 109: 36-44, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-29894845

RESUMO

Protein tyrosine phosphatase 1B (PTP1B) impairs nitric oxide (NO) production and induces endothelial dysfunction in various diseases, including diabetes, septic shock and heart failure. In non-cardiovascular tissues, PTP1B modulates endoplasmic reticulum stress (ERS) however this role has never been assessed in endothelial cells. We evaluated the link between PTP1B, ERS and endothelial dysfunction in mice. Induction of ERS (Tunicamycin) in vivo in mice or ex vivo in mouse arteries led to severe arterial endothelial dysfunction (i.e. reduced flow-dependent, NO mediated dilatation in isolated small mesenteric arteries), and this was prevented by the PTP1B inhibitor trodusquemine and absent in PTP1B-/- mice. Trodusquemine also prevented the Tunicamycin -induced increased arterial levels of the molecular ERS actors 78 kDa glucose-regulated protein (GRP78) and Activating Transcription Factor 6 (ATF6α). Tunicamycin strongly increased the interactions of PTP1B with GRP78 and the activated forms of protein kinase RNA-like endoplasmic reticulum kinase (PERK) and IRE1α (proximity Ligation Assay). Thus, PTP1B plays a central role in the regulation of ERS in the endothelium, and the endothelial protective effect of PTP1B inhibition appears likely due at least in part to reduction of endothelial ERS, notably by promoting PERK protective pathway. Modulation of ER stress via PTP1B inhibitors may be a promising approach to protect the endothelium in cardiovascular diseases.


Assuntos
Estresse do Retículo Endoplasmático/efeitos dos fármacos , Endotélio Vascular/efeitos dos fármacos , Proteína Tirosina Fosfatase não Receptora Tipo 1/metabolismo , Tunicamicina/farmacologia , Vasodilatação/efeitos dos fármacos , Fator 6 Ativador da Transcrição/metabolismo , Animais , Colestanos/farmacologia , Endorribonucleases/metabolismo , Endotélio Vascular/enzimologia , Endotélio Vascular/fisiopatologia , Inibidores Enzimáticos/farmacologia , Proteínas de Choque Térmico/metabolismo , Masculino , Camundongos Endogâmicos BALB C , Camundongos Knockout , Óxido Nítrico/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 1/antagonistas & inibidores , Proteína Tirosina Fosfatase não Receptora Tipo 1/deficiência , Proteína Tirosina Fosfatase não Receptora Tipo 1/genética , Proteínas Serina-Treonina Quinases/metabolismo , Transdução de Sinais/efeitos dos fármacos , Espermina/análogos & derivados , Espermina/farmacologia , eIF-2 Quinase/metabolismo
12.
J Nat Prod ; 81(6): 1357-1367, 2018 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-29893560

RESUMO

Biotransformation of neoruscogenin (NR, 1, spirosta-5,25(27)-diene-1ß,3ß-diol), the major bioactive sapogenin of Ruscus preparations, was carried out with the endophytic fungus Alternaria eureka. Fourteen new biotransformation products (2-15) were isolated, and their structures were elucidated by NMR and HRESIMS data analyses. A. eureka affected mainly oxygenation, oxidation, and epoxidation reactions on the B and C rings of the sapogenin to afford compounds 8-15. In addition to these, cleavage of the spiroketal system as in compounds 2-7 and subsequent transformations provided unusual metabolites. This is the first study reporting conversion of the spirostanol skeleton to cholestane-type metabolites 2-5. Additionally, the cleavage of the C-22/C-26 oxygen bridge yielding a furostanol-type steroidal framework and subsequent formation of the epoxy bridge between C-18 and C-22 in 7 was encountered for the first time in steroid chemistry.


Assuntos
Alternaria/metabolismo , Biotransformação/fisiologia , Espirostanos/metabolismo , Colestanos/metabolismo , Furanos/metabolismo , Espectroscopia de Ressonância Magnética/métodos , Oxirredução , Sapogeninas/metabolismo , Compostos de Espiro/metabolismo , Esteroides/metabolismo
13.
Chembiochem ; 19(13): 1433-1443, 2018 07 04.
Artigo em Inglês | MEDLINE | ID: mdl-29660780

RESUMO

Membrane proteins allow effective communication between cells and organelles and their external environments. Maintaining membrane protein stability in a non-native environment is the major bottleneck to their structural study. Detergents are widely used to extract membrane proteins from the membrane and to keep the extracted protein in a stable state for downstream characterisation. In this study, three sets of steroid-based amphiphiles-glyco-diosgenin analogues (GDNs) and steroid-based pentasaccharides either lacking a linker (SPSs) or containing a linker (SPS-Ls)-have been developed as new chemical tools for membrane protein research. These detergents were tested with three membrane proteins in order to characterise their ability to extract membrane proteins from the membrane and to stabilise membrane proteins long-term. Some of the detergents, particularly the SPS-Ls, displayed favourable behaviour with the tested membrane proteins. This result indicates the potential utility of these detergents as chemical tools for membrane protein structural study and a critical role of the simple alkyl spacer in determining detergent efficacy.


Assuntos
Sistemas de Transporte de Aminoácidos/química , Colestanos/química , Detergentes/química , Oligossacarídeos/química , Receptores Adrenérgicos beta 2/química , Simportadores/química , Proteínas de Bactérias/química , Colestanos/síntese química , Detergentes/síntese química , Humanos , Micelas , Oligossacarídeos/síntese química , Estabilidade Proteica , Salmonella typhimurium/química , Estereoisomerismo
14.
ChemMedChem ; 13(10): 1018-1027, 2018 05 23.
Artigo em Inglês | MEDLINE | ID: mdl-29465814

RESUMO

The emergence of multidrug-resistant bacteria and pathogens has created an urgent need for the development of new antibiotics. Herein we report our investigations into the broad-spectrum activity of an easily prepared water-soluble polyaminosterol compound, namely claramine A1, against both drug-sensitive and drug-resistant Gram-negative and Gram-positive bacterial strains. We also report its peculiar mechanism of action, which differs from that of all the other well-known classes of antibiotics, toward Gram-negative and Gram-positive bacteria. Given their low cytotoxicity, this class of compounds based on claramine A1 could constitute an effective response to combat the emergence of multidrug-resistant bacteria and nosocomial diseases.


Assuntos
Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Colestanos/química , Colestanos/farmacologia , Espermina/análogos & derivados , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Humanos , Larva/efeitos dos fármacos , Testes para Micronúcleos , Estrutura Molecular , Mariposas/efeitos dos fármacos , Espermina/química , Espermina/farmacologia , Relação Estrutura-Atividade
15.
J Am Chem Soc ; 140(3): 916-918, 2018 01 24.
Artigo em Inglês | MEDLINE | ID: mdl-28930454

RESUMO

Proteins in the hedgehog family undergo self-catalyzed endoproteolysis involving nucleophilic attack by a molecule of cholesterol. Recently, a conserved aspartate residue (D303, or D46) of hedgehog was identified as the general base that activates cholesterol during this unusual autoprocessing event; mutation of the catalyzing functional group (D303A) reduces activity by >104-fold. Here we report near total rescue of this ostensibly dead general base mutant by a synthetic substrate, 3ß-hydroperoxycholestane (3HPC) in which the sterol -OH group is replaced by the hyper nucleophilic -OOH group. Other hedgehog point mutants at D303, also unreactive with cholesterol, accepted 3HPC as a substrate with the rank order: WT > D303A ≈ D303N ≫ D303R, D303E. We attribute the revived activity with 3-HPC to the α-effect, where tandem electronegative atoms exhibit exceptionally high nucleophilicity despite relatively low basicity.


Assuntos
Colestanos/metabolismo , Colesterol/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , Proteínas Hedgehog/metabolismo , Animais , Catálise , Domínio Catalítico , Proteínas de Drosophila/química , Drosophila melanogaster/química , Proteínas Hedgehog/química , Especificidade por Substrato
16.
Sci Rep ; 7(1): 16375, 2017 11 27.
Artigo em Inglês | MEDLINE | ID: mdl-29180806

RESUMO

Cholesterol oxidase catalyzes the oxidation and isomerization of the cholestane substrates leading to the addition of a hydroxyl group at the C3 position. Rational engineering of the cholesterol oxidase from Pimelobacter simplex (PsChO) was performed. Mutagenesis of V64 and F70 improved the catalytic activities toward cholestane substrates. Molecular dynamics simulations, together with structure-activity relationship analysis, revealed that both V64C and F70V increased the binding free energy between PsChO mutants and cholesterol. F70V and V64C mutations might cause the movement of loops L56-P77, K45-P49 and L350-E354 at active site. They enlarged the substrate-binding cavity and relieved the steric interference with substrates facilitating recognition of C17 hydrophobic substrates with long side chain substrates.


Assuntos
Colestanos/química , Colestanos/metabolismo , Colesterol Oxidase/química , Colesterol Oxidase/metabolismo , Sítios de Ligação , Domínio Catalítico , Colesterol Oxidase/genética , Cromatografia Gasosa-Espectrometria de Massas , Cinética , Simulação de Dinâmica Molecular , Mutagênese Sítio-Dirigida , Ligação Proteica , Conformação Proteica , Relação Estrutura-Atividade , Especificidade por Substrato
17.
Clin Sci (Lond) ; 131(20): 2489-2501, 2017 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-28899902

RESUMO

Cardiovascular disease (CVD) is the most prevalent cause of mortality among patients with type 1 or type 2 diabetes, due to accelerated atherosclerosis. Recent evidence suggests a strong link between atherosclerosis and insulin resistance, due to impaired insulin receptor (IR) signalling. Here, we demonstrate that inhibiting the activity of protein tyrosine phosphatase 1B (PTP1B), the major negative regulator of the IR prevents and reverses atherosclerotic plaque formation in an LDLR-/- mouse model of atherosclerosis. Acute (single dose) or chronic PTP1B inhibitor (trodusquemine) treatment of LDLR-/- mice decreased weight gain and adiposity, improved glucose homeostasis and attenuated atherosclerotic plaque formation. This was accompanied by a reduction in both, circulating total cholesterol and triglycerides, a decrease in aortic monocyte chemoattractant protein-1 (MCP-1) expression levels and hyperphosphorylation of aortic Akt/PKB and AMPKα. Our findings are the first to demonstrate that PTP1B inhibitors could be used in prevention and reversal of atherosclerosis development and reduction in CVD risk.


Assuntos
Aorta/efeitos dos fármacos , Doenças da Aorta/prevenção & controle , Aterosclerose/prevenção & controle , Colestanos/administração & dosagem , Inibidores Enzimáticos/administração & dosagem , Placa Aterosclerótica , Proteína Tirosina Fosfatase não Receptora Tipo 1/antagonistas & inibidores , Receptores de LDL/deficiência , Espermina/análogos & derivados , Proteínas Quinases Ativadas por AMP/metabolismo , Animais , Aorta/enzimologia , Aorta/patologia , Doenças da Aorta/enzimologia , Doenças da Aorta/genética , Doenças da Aorta/patologia , Aterosclerose/enzimologia , Aterosclerose/genética , Aterosclerose/patologia , Biomarcadores/sangue , Glicemia/efeitos dos fármacos , Glicemia/metabolismo , Quimiocina CCL2/metabolismo , Colesterol/sangue , Dieta Hiperlipídica , Modelos Animais de Doenças , Esquema de Medicação , Predisposição Genética para Doença , Homeostase , Masculino , Camundongos Knockout , Fenótipo , Fosforilação , Proteína Tirosina Fosfatase não Receptora Tipo 1/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptores de LDL/genética , Transdução de Sinais/efeitos dos fármacos , Espermina/administração & dosagem , Fatores de Tempo , Triglicerídeos/sangue , Perda de Peso
18.
Molecules ; 22(8)2017 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-28757596

RESUMO

Previous phytochemical studies of the bulbs of Ornithogalum saundersiae, an ornamental perennial plant native to South Africa, resulted in the isolation of 29 new cholestane glycosides, some of which were structurally unique and showed potent cytotoxic activity against cultured tumor cell lines. Therefore, we aimed to perform further phytochemical examinations of methanolic extracts obtained from Ornithogalum saundersiae bulbs, isolating 12 new cholestane rhamnosides (1-12) and seven known compounds (13-19). The structures of the new compounds (1-12) were identified via NMR-based structural characterization methods, and through a sequence of chemical transformations followed by spectroscopic and chromatographic analysis. The cytotoxic activity of the isolated compounds (1-19) and the derivatives (1a and 6a) against HL-60 human promyelocytic leukemia cells and A549 human lung adenocarcinoma cells was evaluated. Compounds 10-12, 16, and 17 showed cytotoxicity against both HL-60 and A549 cells. Compound 11 showed potent cytotoxicity with an IC50 value of 0.16 µM against HL-60 cells and induced apoptotic cell death via a mitochondrion-independent pathway.


Assuntos
Adenocarcinoma/tratamento farmacológico , Antineoplásicos Fitogênicos , Colestanos , Glucosídeos , Leucemia Promielocítica Aguda/tratamento farmacológico , Neoplasias Pulmonares/tratamento farmacológico , Ornithogalum/química , Células A549 , Adenocarcinoma/metabolismo , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/farmacologia , Colestanos/química , Colestanos/farmacologia , Glucosídeos/química , Glucosídeos/farmacologia , Células HL-60 , Humanos , Leucemia Promielocítica Aguda/metabolismo , Neoplasias Pulmonares/metabolismo
19.
J Phys Chem B ; 121(20): 5209-5217, 2017 05 25.
Artigo em Inglês | MEDLINE | ID: mdl-28467087

RESUMO

The clustering of molecules is an important feature of plasma membrane organization. It is challenging to develop methods for quantifying membrane heterogeneities because of their transient nature and small size. Here, we obtained evidence that transient membrane heterogeneities can be frozen at cryogenic temperatures which allows the application of solid-state experimental techniques sensitive to the nanoscale distance range. We employed the pulsed version of electron paramagnetic resonance (EPR) spectroscopy, the electron spin echo (ESE) technique, for spin-labeled molecules in multilamellar lipid bilayers. ESE decays were refined for pure contribution of spin-spin magnetic dipole-dipolar interaction between the labels; these interactions manifest themselves at a nanometer distance range. The bilayers were prepared from different types of saturated and unsaturated lipids and cholesterol (Chol); in all cases, a small amount of guest spin-labeled substances 5-doxyl-stearic-acid (5-DSA) or 3ß-doxyl-5α-cholestane (DChl) was added. The local concentration found of 5-DSA and DChl molecules was remarkably higher than the mean concentration in the bilayer, evidencing the formation of lipid-mediated clusters of these molecules. To our knowledge, formation of nanoscale clusters of guest amphiphilic molecules in biological membranes is a new phenomenon suggested only recently. Two-dimensional 5-DSA molecular clusters were found, whereas flat DChl molecules were found to be clustered into stacked one-dimensional structures. These clusters disappear when the Chol content is varied between the boundaries known for lipid raft formation at room temperatures. The room temperature EPR evidenced entrapping of DChl molecules in the rafts.


Assuntos
Colestanos/química , Óxidos N-Cíclicos/química , Bicamadas Lipídicas/química , Lipídeos/química , Espectroscopia de Ressonância de Spin Eletrônica , Modelos Moleculares , Solubilidade , Marcadores de Spin , Temperatura
20.
Phytochemistry ; 136: 125-132, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28139298

RESUMO

Phytochemical investigation of the tubers of Ophiopogon japonicus led to the isolation of five previously undescribed steroidal saponins, ophiojaponins A-E, together with twelve known ones. The structures of these isolated compounds were elucidated by detailed spectroscopic analyses and chemical methods. Ophiojaponins A-C are rare naturally occurring C29 steroidal glycosides possessing a homo-cholestane skeleton with an aromatized ring E. Ruscogenin 1-O-α-L-rhamnopyranosyl-(1 â†’ 2)-4-O-sulfo-ß-D-fucopyranosido-3-O-ß-D-glucopyranoside was isolated as single component and its full spectroscopic data was reported for the first time. The isolated steroidal saponins were evaluated for their cytotoxicities against two human tumor cell lines MG-63 and SNU387. Among them, five known spirostane-type glycosides showed cytotoxic activity against both MG-63 and SNU387 cell lines with IC50 values ranging from 0.76 to 27.0 µM.


Assuntos
Antineoplásicos Fitogênicos/isolamento & purificação , Colestanos/isolamento & purificação , Medicamentos de Ervas Chinesas/isolamento & purificação , Ophiopogon/química , Tubérculos/química , Saponinas/isolamento & purificação , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/farmacologia , Colestanos/química , Colestanos/farmacologia , Ensaios de Seleção de Medicamentos Antitumorais , Medicamentos de Ervas Chinesas/química , Medicamentos de Ervas Chinesas/farmacologia , Estrutura Molecular , Saponinas/química , Saponinas/farmacologia , Estereoisomerismo
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